EghtesadOnline: The second phase of Tehran's seventh water treatment plant (Mamlou Treatment Plant) became operational, managing director of Tehran Province Water and Wastewater Company said. It will help improve the quality of potable water in the south parts of the sprawling capital.

“The $80 million facility (in Pakdasht County, 25 km southeast of Tehran) has a capacity to treat 160 million cubic meters of water per annum,” Mohammadreza Bakhtiari was quoted as saying by IRNA.

Built over 11 hectares, the plant will help improve the quality of tap water for at least 2 million people, Financial Tribune reported.

“Piped water in Tehran’s downtown districts, namely Shoush, Khavaran, Baqerabad, Khavarshahr, Varamin, Pakdasht, Qiamdasht, Naziabad, Afsariyeh and Yaftabad was mixed with underground water. But now they will be supplied with surface water (from dams) that has better quality.”

An 80-km pipeline connects Tehran's seventh water treatment plant to Mamlou dam (built on Jajroud River). The first phase of the project came on stream in 2015.

Almost 30% of Tehran's water is supplied from (rapidly depleting) underground water resources and the new plant will help gradually cut this demand to 20%.

Moreover, the new phase will help decommission 150 water wells in Tehran, most of which are in the Varamin Plain (40 km southeast of the capital) that is sinking due to land subsidence.

Land Subsidence

The earth sinks in some plains in Tehran Province by about 0.5 to 1 millimeter every day, and conditions are more critical in Shahriar and Varamin counties in southwest and south Tehran, Bakhtiari said.

“An annual 31 centimeters of land subsidence is reported in Tehran Province. Over 1.5 billion cubic meters of water is extracted from the ground in the capital every year.”

Land subsidence is defined by scientific references as a gradual settling or sudden sinking of the earth's surface owing to subsurface movement of earth materials.

Principal causes are aquifer-system compaction, drainage of organic soils, underground mining, gas and oil extraction as well as earthquakes.

Nevertheless, the main reason of land subsidence in Iran is injudicious groundwater extraction that has caused serious concern among conservationists, environmental/economic experts, academia and water managers.

The disturbing trend has gone way beyond the global norm of annual 4 millimeters land settling. “More than 200mm of land subsidence per year is considered critical,” he said,

Although reversing land subsidence is almost impossible, slowing its progress is doable provided the government and public cooperate. Reducing consumption and reforming farming methods is the key to addressing the worsening water problems.

Iran’s annual water consumption tops 100 billion cubic meters, while the country only has 90 bcm of renewable sources. How this yawning deficit will be reduced in the coming years is a question few officials are able or willing to answer.

According to the TPWWC chief, subscribers in the province consumed close to 960 million cubic meters of water in the past 10 months (March 2019-Jan 2020) -- up 6% or 50 mcm compared to the corresponding period in the previous year.

Tehran consume 35% of the entire water produced in the country and accounts for 18% of the total population of 82 million.

According to Bakhtiari, the production of each cubic meter of drinking water costs the government 25,000 rials ($0.20) while it is sold for hardly 6,000 rials ($0.05). This largesse in the form of costly subsidies has to come to an end sooner rather than later, conservationists and agro experts say.

Ongoing Plans

The official went on to say that expediting construction of wastewater treatment plants in Tehran is on the TPWWC agenda.

Pipe-laying operations have been undertaken in most districts of the expanding capital to connect households, businesses and industrial sectors to the wastewater network.

“Laying sewer pipes has progressed by 75%, however when it comes to the constructing wastewater treatment plants the progress is slow, hovering around 40%.”

Of the 9,000km wastewater network designed for the capital, 7,000 km are in place.

“We are working on the Firouz Bahram Wastewater Treatment Plant in the west, which is the second largest in the country after the South Wastewater Treatment Plant,” he added.

Firouz Bahram plant is planned to come online by 2021 and will be used by 2.8 million people.